Studies of chemical metabolism and disposition are designed to provide both applied knowledge in support of chronic toxicity tests conducted by the National Toxicology Program and basic knowledge of those chemical structure and property relationships which determine toxicity. Studies of furan indicated that the disposition of this compound is highly dependent upon both route of administration and the dose administered. Furan is eliminated primarily in the exhaled air. Metabolism of furan involves the formation of reactive intermediates which covalently bind to both protein and nucleic acids. Studies of dermal absorption of 2,3-dibromopropanol indicate that it is absorbed through the skin, but most of the dose applied to skin volatilizes and may be inhaled or lost to the atmosphere.